2,393 research outputs found
Anisotropic magnetic diffuse scattering in an easy-plane type antiferromagnet ErNiGe
We report on neutron scattering studies of a rare earth intermetallic
compound ErNiGe. Polarized neutron scattering experiments revealed
that the magnetic ordered moment lies in ab-plane. Taking account of
a lack of the third higher harmonic reflection, ErNiGe is
considered to have a helical magnetic structure. The magnetic scattering
profiles along the - and the -directions are well
described by the sum of Gaussian and modified-Lorentzian terms, even far below
, indicating that short-range orders coexist with a
long-range order. Interestingly, the modified-Lorentzian-type diffuse
scattering is not present in the profiles along the -direction.
The anisotropy of the diffuse scattering suggests that the short-range-order
consists of one dimensional long-range helices along the c-axis.Comment: 4 pages, to be published in J. Phys.: Condens. Matter (HFM2008
Anomalous phase of MnP at very low field
Manganese phosphide MnP has been investigated for decades because of its rich
magnetic phase diagram. It is well known that the MnP exhibits the
ferromagnetic phase transition at \Tc=292 K and the helical magnetic phase
below \TN=47 K at zero field. Recently, a novel magnetic phase transition was
observed at K when the magnetic field is lower than 5 Oe. However,
the nature of the new phase has not been illuminated yet. In order to reveal
it, we performed the AC and the DC magnetization measurements for a single
crystal MnP at very low field. A divergent behavior of the real and the
imaginary part of the AC susceptibility and a sharp increase of the DC
magnetization was observed at , indicating the magnetic phase transition
at . Furthermore a peculiar temperature hysteresis was observed: namely,
the magnetization depends on whether cooling sample to the temperature lower
than \TN or not before the measurements. This hysteresis phenomenon suggests
the complicated nature of the new phase and a strong relation between the
magnetic state of the new phase and the helical structure.Comment: 4 pages, 2 figure
<Session 5: Wildlife Tracking I>Simultaneous measurements of breaths and energy expenditure reveal the dive tactics of sea turtles
19–22 May 2022 Kyoto, JapanAir-breathing divers are assumed to have evolved to apportion their time between surface and underwater periods to maximize the benefit gained from diving activities. However, whether they change their time allocation depending on the aim of the dive is still unknown. This may be particularly crucial for 'surfacers' because they dive for various purposes in addition to foraging. In this study, we counted breath events at the surface and estimated oxygen consumption during resting, foraging, and other dives in 11 green turtles (Chelonia mydas) in the wild. Breath events were counted by a head-mounted acceleration logger or direct observation based on an animal-borne video logger, and oxygen consumption was estimated by measuring overall dynamic body acceleration. Our results indicate that green turtles maximized their submerged time, following this with 5-7 breaths to replenish oxygen for resting dives. However, they changed their dive tactic during foraging and other dives; they surfaced without depleting their oxygen content, followed by only a few breaths for effective foraging and locomotion. These dichotomous surfacing tactics would be the result of behavioral modifications by turtles depending on the aim of each dive
Indication of antiferromagnetic interaction between paramagnetic Co ions in the diluted magnetic semiconductor ZnCoO
The magnetic properties of ZnCoO ( and 0.10) thin films,
which were homo-epitaxially grown on a ZnO(0001) substrates with varying
relatively high oxygen pressure, have been investigated using x-ray magnetic
circular dichroism (XMCD) at Co core-level absorption edge. The line
shapes of the absorption spectra are the same in all the films and indicate
that the Co ions substitute for the Zn sites. The magnetic-field and
temperature dependences of the XMCD intensity are consistent with the
magnetization measurements, indicating that except for Co there are no
additional sources for the magnetic moment, and demonstrate the coexistence of
paramagnetic and ferromagnetic components in the homo-epitaxial
ZnCoO thin films, in contrast to the ferromagnetism in the
hetero-epitaxial ZnCoO films studied previously. The analysis of
the XMCD intensities using the Curie-Weiss law reveals the presence of
antiferromagnetic interaction between the paramagnetic Co ions. Missing XMCD
intensities and magnetization signals indicate that most of Co ions are
non-magnetic probably because they are strongly coupled antiferromagnetically
with each other. Annealing in a high vacuum reduces both the paramagnetic and
ferromagnetic signals. We attribute the reductions to thermal diffusion and
aggregation of Co ions with antiferromagnetic nanoclusters in
ZnCoO.Comment: 21 pages, 7 figures, accepted for Physical Review
Optical and structural properties of GaAs/GaInP quantum wells grown by Chemical Beam Epitaxy
In this work we investigated the optical and structural properties of GaAs/GaInP quantum wells (QW) grown by Chemical Beam Epitaxy (CBE). The samples were characterized by photoluminescence (PL), photoluminescence excitation (PLE) and transmission electron microscopy (TEM). Simulations of the quantum well potential profiles, using the Van De Walle-Martin model, supplemented by our experimental results, allowed us to associate the interface properties with the growth procedures. We concluded that a thin GaP layer grown at the interface improves its quality and also that the observed broad emission band in the PL spectrum is related to quaternary Ga1-xIn xAs1-yPy.620622Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação para o Desenvolvimento da UNESP (FUNDUNESP
Photoemission and x-ray absorption studies of valence states in (Ni,Zn,Fe,Ti)O thin films exhibiting photo-induced magnetization
By means of photoemission and x-ray absorption spectroscopy, we have studied
the electronic structure of (Ni,Zn,Fe,Ti)O thin films, which
exhibits a cluster glass behavior with a spin-freezing temperature of
K and photo-induced magnetization (PIM) below . The Ni and Zn
ions were found to be in the divalent states. Most of the Fe and Ti ions in the
thin films were trivalent (Fe) and tetravalent (Ti),
respectively. While Ti doping did not affect the valence states of the Ni and
Zn ions, a small amount of Fe ions increased with Ti concentration,
consistent with the proposed charge-transfer mechanism of PIM.Comment: 4 pages, 4 figure
Non-Fermi-Liquid Scaling in Ce(Ru_{0.5}Rh_{0.5})_2Si_2
We study the temperature and field dependence of the magnetic and transport
properties of the non-Fermi-liquid compound Ce(Ru_{1-x}Rh_x)_2Si_2 at x=0.5.
For fields 0.1T the experimental results show signatures of the
presence of Kondo-disorder, expected to be large at this concentration. For
larger fields, however, magnetic and transport properties are controlled by the
coupling of the conduction electrons to critical spin-fluctuations. The
temperature dependence of the susceptibility as well as the scaling properties
of the magnetoresistance are in very good agreement with the predictions of
recent dynamical mean-field theories of Kondo alloys close to a spin-glass
quantum critical point.Comment: 4 pages, 4 figures. Improved discussion. To appear in Phys. Rev. Let
Soft x-ray magnetic circular dichroism study of weakly ferromagnetic ZnVO thin film
We performed a soft x-ray magnetic circular dichroism (XMCD) study of a
ZnVO thin film which showed small ferromagnetic moment. Field and
temperature dependences of V 2 XMCD signals indicated the coexistence of
Curie-Weiss paramagnetic, antiferromagnetic, and possibly ferromagnetic V ions,
quantitatively consistent with the magnetization measurements. We attribute the
paramagnetic signal to V ions substituting Zn sites which are somewhat
elongated along the c-axis
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